David Cameron is coming under fresh pressure to force out NHS chief executive Sir David Nicholson this afternoon. The health boss has had to apologise to the Public Accounts Committee, after his evidence yesterday was directly contradicted by whistleblower Gary Walker’s testimony to the Health Select Committee today.

Nicholson told the PAC that Walker ‘didn’t identify himself as a whistleblower at that moment in time, nor did he raise with me any issues of patient safety’. But today Walker produced a letter which said ‘I assume the Department of Health has a policy on whistleblowing and would therefore like this letter to be considered in that context’.

Nicholson’s letter of clarification to PAC chair Margaret Hodge, sent this afternoon, said: ‘I have now had the opportunity to review the correspondence and would like to confirm that when Gary Walker wrote to me in July 2009 he did indeed ask to be considered as a whistleblower.’ He added that he had commissioned an independent investigation into the allegations made by Walker.

Charlotte Leslie, the Tory MP who has been campaigning for Nicholson to go, tells me she is going to raise this with David Cameron as she believes this blunder shows that Nicholson is not fit to run the NHS. She says:

‘It’s either a really serious question of integrity, or it’s a really serious question of incompetence. It’s not something that he wouldn’t have researched because he was appearing in front of the Public Accounts Committee, which was looking at gagging orders and whistleblowing. It’s quite clear that he’s got to go.’

David Cameron and Jeremy Hunt haven’t shifted their positions at all on Nicholson in the past few days, preferring instead to talk about board members at the Trust and questions for the Labour party. But as Leslie argues, giving incorrect evidence to a select committee won’t help his bid to stay in the job.

Tags: Mid-Staffordshire, NHS, Sir David Nicholson, UK politics